Keyhole-guard.



G. P. C. MULLER.

KEYHOLB GUARD. APPLICATION FILED 1.411,18, 1910.

Patented Jlvlly 26, 1910.

ATTORNEY fue mmkls PETERS co.. wasumnrou, v. c.

Uff srrs GEORG-E F. C. MULLER, OF SAN FRANCISCO, CALIFORNIA.

Specification of Letters Patent. Patllijed July 26, 1910, Application filed January 18, 1910.

Serial No. 538,781.

To all whom t may concern.'

Be it known that I, GEORGE F. C. MULLER, a `citizen of the United States, residing at San Francisco, in the county of San Francisco and State of California, have invented a certain new and useful Keyhole-Guard, of which the following is a specification.

The object of the invention is to provide means attached to a door key, or other key havinga common lock for anchoring said key in the key hole of the lock, thereby preventing the turning of the key from the out- 1side, or from the inside except with a special rey.

In the accompanying drawing, Figure 1 is a side view of the key proper detached; Fig. 2 is a side view of the key hole plug, detached; Fig. 3 is a side view, partly in section, of the auxiliary lock, showing also part of the stem of the key attached thereto, but the key hole plug being removed; Fig. 4 is a side view of the complete device in its unlocked position; Fig. 5 is a similar view taken at right angles to Fig. 4; Fig. 6 is an edge view of a portion of a door, showing the key, with the device attached thereto7 in its locking position.

Referring to the drawing, 1 indicates a key having a stem 2, a bit 3 on the end of said stem, and an annular shoulder 4 adjacent to said bit. The part 5 ofthe stein behind said shoulder is cylindrical and thereon is passed a cylindrically apertured portion 6 of a key plug 7 which is formed with a plate 8 adapted Ito enter a key hole, and an enlarged portion or arm 9 extending from the cylindrical portion 6 in the same general direction as the plate, being formed at its outer end with a projection or lock catch 10 extending from said arm in the opposite direction of said plate. The cylindrically apertured portion 6 of said key hole plug having been passed on to the part 5 of the stem as far as the shoulder 4, there is then secured to said stem, in any suitable manner, a hinge member 11, having a pintle hole 12 therethrough. Said hinge member is secured upon the key so that the direction of the pintle hole is at right angles to the plane of the bit. Hinged upon said hinge member is a plug lock 13, which is similar to an ordinary padlock, ex cept that instead of the arched keeper common in padlocks, there is substituted the key stem 2, pivoted, as before described, to one side of said padlock, while into the usual socket 14 in the padlock, at the opposite side of the same end, there is received the lock catch 10, the key 15 of the padlock being. ini serted into the other end thereof. The hinge member 11 is formed with a flattened seat 16 against whichv a fiat spring 17, secured within the plug lock, presses, to hold the plug lock at an angle to the key hole plug when the plug lock is not locked thereto.

18 indicates a door and 19 a lock having a key hole to which my invention is shown-as applied.

The mode of use of the device is as follows. The key 1 is inserted in the key hole of the lock 19 the full distance t'o permit the plug 7 to also enter said key hole and be immovable therein. The key can however turn within the plug, and it is so turned to lock the door. If in this position, the plug 'lock 13 does not register accurately with the arm of the key hole plug 7, it is turned so as to register therewith, and is snapped down upon the lock catch so as to close and lock thereto in the manner of an ordinary spring padlock. The operation is then completed. The key cannot be turned in the lock from the outside, because it is held from turning by the plug lock 13 attached thereto, and locked to the lock catch 10, which lock catch is itself prevented turning by means of a key hole plug being held in the key hole. More over the key cannot be turned from the inside of the door except by first applying the key 15 to the plug lock to unlock the same.

1. The combination of a key having a stem and a bit, a plug lock pivotally connecte ed at one side thereof to the end of said stem to swing in a plane transverse to the plane of the bit, a key hole plug having a sleeve portion surrounding the stem, a portion extending outward therefrom adapted to enter the key hole, and an outwardly extended lock catch, the plug lock having a socket to receive said lock catch and provided with means for locking it therein, substantially as described.

2. The combination of a key having a stem, an annular shoulder thereon, and a bit, a plug lock pivotally connected at one side thereof to the end of said stem to swing in a plane transverse to the plane of the bit, a key hole plug having a sleeve portion surrounding the stem between said end and shoulder, a portion extending outward therefrom adapted to enter the key hole, and an outwardly extended lock catch, the plug lock having a socket to receive said lock catch and provided with means for locking it therein, substantially as described.

3. The combination of a key having a stein and a bit, a plug rotatably mounted upon said stem and having a portion adapted to enter a key hole and an arm extending at right angles to the axis of rotation of said plug on said bit, and a plug lock, pivotally connected to one of the tivo elements, the end of said stem and the outer end of said arm, and detachably connected to the other element, said plug lock being provided with means for locking said detachable connection, substantially as described.

4f. The combination of a key having a stem and a bit, a plug rotatably mounted upon said stem and having a portion adapted `to enter a key hole and an arm extending at right angles to the axis of rotation of said plug on said bit, and a plug lock, pivotally connected to one of the tvvo elements, the end of said stem and the outer end of said arm, and detachably connected to the other element, said plug lock being provided With means located at the end remote from said pivotal and detachable connections to receive a key for locking said detachable connection, substantially as described.

V5. The combination of a key having a stem and a bit, a plug rotatably mounted upon said stein and having a portion adapted to enter a key hole and an arm extending at right angles to the axis of rotation of said plug on said bit, a plug lock, pivotally connected to one of the tivo elements, the end of said stem and the outer end of said arm, and detachably connected to the other element, said plug lock being provided With means for locking said detachable connection, and a spring for normally pressing said plug lock avvay :trom said plug, substantially as described.

6. In combination with a key, a plug lock pivoted to the stem end of said key, and a key hole plug having a lock catch adapted to be interlocked with said plug lock, said plug lock having a spring adapted to hold the same in a diagonal position upon the stem end of said key, substantiallyl as described.

In testimony whereof I have hereunto set my hand in the presence of tWo subscribing Witnesses.

GEORGE E. G. MULLER.

Witnesses:

FRANK L. OWEN, W. M. BOWERS. 

